Patent GB-765969-A (GB)
Title: Improvements in or relating to electrical telecommunication systems
Inventor: SCOWCROFT JOHN
IPC: H04Q3/42
Filed: 1953-12-04
Abstract: 765,969. Automatic exchange systems. GENERAL ELECTRIC CO., Ltd. Feb. 24, 1955 [Dec. 4, 1953], No. 33773/53. Class 40 (4). Information received in the form of trains of electrical impulses is translated into other trains of electrical impulses by a translator which is available to any one of a plurality of registers which are in turn available to a greater plurality of impulse-receiving circuits (referred to hereinafter, and in the Specification, as " apparatus groups "); information required by the translator for a particular translation is stored by both the relevant apparatus group and the register engaged by it. As shown, a plurality of apparatus groups such as 91 has access to a lesser plurality of registers such as 93 all of which have access to a common translator 99 which is employed to translate the first three digits (the A, B and C- digits) of a dialled number into a routing code. In a call requiring the use of the translator, the calling party first dials a prefix digit which sets a previously seized switch 90 to the corresponding level where it hunts and seizes a free apparatus group 91. A uniselector 92 hunts and seizes a free register 93 while the dialled A-digit is received by a uniselector 94 which accordingly selects one of nine motor-driven uniselectors TA-TJ in the translator 99. The B and C-digits are received by the seized register 93 on two uniselectors (the B and C-digit switches) and a start signal is then applied by way of lead 97 to an allotter 96 associated with the translator 99. The allotter, if free, steps to the position corresponding to the calling register 93. The B and C-digit switches now apply marking potentials to particular contacts, characteristic of the B and C-digits, in two banks of the uniselector, say TA, selected by the A- digit switch, so that the selected uniselector TA finds marking on both banks in only one position. For example, the B-digit switch may mark all the third decade of contacts in one bank of TA while the C-digit switch marks the ninth contact of each decade in the second bank. Then TA will encounter both markings in its 29th position only. The remaining banks of TA are divided into two groups, and the choice of the group to be used depends upon the value of the B-digit. When TA has stepped to the marked position, signals are sent over the wipers of the chosen group to a cross-connecting frame 98, the resulting output from the frame 98 being recorded on groups of relays in the register 93 and in the apparatus group 91. The translator 99 is now released. The register 93 may either have several groups of relays, each group determining one digit of the routing code, or it may have a single group of relays which determines the first digit of the routing code at this stage and subsequently re-engages the translator to obtain the second digit, and so on if necessary. The operation of the selected relays of the group applies a marking to a corresponding contact in a bank of a switch which is then stepped to the marked position under the control of a self-interrupting relay which simultaneously sends the impulses of the routing code digit over the lead 100. The numerical digits of the wanted number have been stored in the register 93 and are transmitted in a similar manner after the transmission of the routing code has caused the connection to be extended to the wanted exchange. Long-distance calls. A further translation process at an intermediate exchange may be required, and in this case the original A, B and C-digits may be re-transmitted between the routing code and the numerical digits. Metering. The relays operated in the apparatus group 91 by the output of the translator cross-connecting frame 98 determine the fee rate to be charged for the call by connecting a lead from the calling subscriber's meter to contacts correspondingly spaced in a bank of a constantly-stepping switch, so that impulses are sent to the meter at the required rate.